Light projection device



E. M. BEESLEY LIGHT PROJECTION DEVICE May 7, 1957 Filed Dec. 22, 1954 ilk Inventor Edward M. Beesle y M 0 14 His ttorney LIGHT PROJECTION DEVICE Edward M. Beesley, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application December 22, 1954, Serial No. 476,921.

6 Claims. (Cl. 313-115) This invention relates in general to light projection devices and more particularly to a combination airplane rates atent O landing and taxiing headlight for selectively projecting either a landing beam or a taxiing beam. Still more particularly the invention relates to an electric incandescent lamp suitable for such purpose and to a mount construction therefor.

On many types of airplanes, it is common practice to i provide the airplane with light-projection means for producing either a landing beam for use when the airplane is making a landing, or a taxiing beam for use when the airplane is taxiing about the air field. Heretofore, the landing and taxiing beams have been provided by separate light-projection devices or lamps mounted on the airplane. However, because of space limitation on certain types of airplanes, and also in view of the desirability of reducing the number and weight of parts, a need has developed for a combination landing and taxiing headlight or lamp which will operate to selectively project either a landing beam or a taxiing beam, at the choosing of the pilot. Generally, such landing beams are in the form of a narrow spot beam of the order of 500,000 maximum beam candlepower or so, while the taxiing beams are in the form of a relatively wide flood beam of the order of 50,000 maximum beam candlepower or so.

It is an object of my invention, therefore, to provide a light-projection device for airplanes which is capable of selectively projecting either a landing beam or a taxiing beam conforming, in general, to the above-mentioned re quirements therefor and substantially free of dark areas or voids.

Another object of my invention is to provide a combination airplane landing and taxiing incandescent lamp which is selectively operable to produce either a landing or a taxiing beam of the above-mentioned general character and substantially free of dark areas vor voids.

Still another object of my invention is to provide a twofilament airplane landing and taxiing lamp which is selectively operable to produce either a landing or a taxiing beam of the above-mentioned general character and having the two filaments thereof constructed and arranged to produce one of the required beams by parallel operation of the filaments and the other beam by independent operation of one of the filaments.

A further object of my invention is to provide an improved mount construction for such a combination airplane landing and taxiing lamp which is of simple construction and easy to manufacture.

Briefly stated, in accordance with one aspect of my invention, a relatively high wattage main filament in the form of a linear coil is disposed axially of and approximately at the focus of an approximately paraboloidal reflector, and a supplementary linear coil filament of somewhat lower wattage than the main filament is disposed above the main filament in a position extending transversely of the reflector axis. Current connections are provided to the respective filaments to enable the selective operation either of the supplementary filament alone "ice to provide a taxiing beam, or of the two filaments in parallel to provide a landing beam.

Further objects and advantages of my invention will appear from the following detailed description of a species thereof and from the accompanying drawing.

In the drawing, Fig. 1 is a horizontal sectional view of an electric incandescent lamp according to my invention; and

Fig. 2 is a perspective view, on an enlarged scale, of the mount structure of the lamp.

Referring to the drawing, the invention is there shown as applied to a self-contained reflector-typeincandescent lamp of the sealed beam type described and claimed in U. S. Patent 2,148,314, D. K. Wright, and comprising a sealed glass envelope or bulb 1 consisting of preformed pressed glass reflector and cover glass sections 2 and 3, respectively, sealed together at their peripheries by fusion, as indicated at 4. The concave inner surface 5 of the reflector section 2 is formed of approximately paraboloidal shape and is covered with a reflecting coating 6 of aluminum, silver or other similar light-reflective material.

Mounted on the rear outer side of the reflector section 2 at the region of the apex or center thereof is a base structure 7 of the general type shown and described in U. S. Patent 2,272,512, Cotman, and comprising a plural ity (3) of terminal contacts 8 in the form of metal straps or lugs which are suitably fastened, as by soldering or brazing for instance, to the closed nippled ends 9 of respective metal ferrules or thimbles 10. The contact lugs 8 are provided with screw terminals 11 for connecting current supply wires thereto. The ferrules 10 are formed and with two of the thimbles disposed in an axial plane metal.

of the reflector section. The envelope 1 is provided with an exhaust tubulation 14 communicating with the interior of the envelope through an exhaust aperture 15 in the envelope wall at the apex of the reflector section 2. After exhaustion of the envelope through the tubulation 14 and, if desired, introduction of a suitable gas filling such as nitrogen or argon, the tubulation 14 is sealed or tippedoff as indicated at 16.

Mounted within the envelope 1 and supported solely from the metal ferrules 10 in spaced relation to the envelope wall is a lamp mount structure 17 according to the invention and comprising a plurality (3) of rigid lead-in conductors or inleads 18, 19 and 20 suitably secured at their outermost ends within the nipples 9 of respective ferrules 10, as by hard solder 21 as shown. From the ferrules 10, the lead-in conductors 18, 19 and 20 extend through the openings 13 in the wall of the reflector section 2 and into the envelope 1 in more or less parallel spaced relation. Two of the lead-in conductors, i. e., the two lead-in conductors 18 and 19 which are disposed in an axial plane of the reflector section, are connected at their innermost ends to the opposite ends of a main filament 22 preferably in the form of a linear coiled-coil wire of tungsten or other suitable refractory For the purposes of the invention, the main filament 22 is of relatively high wattage, for example around 600 watts, with a rated voltage of around 28 volts. The filament 22 is supported on the conductors 18, 19 in a position symmetrically disposed with respect to the focus of the reflector section 2 and with the axis of the coil coja igned with the axis of the reflector section. The filament 22 is formed with .straight, i. e., uneoiled, end leg portions 23 extending laterally of the coil and across the conductors 18, 19, and they are provided with tightfitting tungsten Wire slip-over coils 24 which are welded to the respective conductors 1'8, 19 to thereby 'form the filament connections or. joints. The filament joints are preferably reinforced by means of thin sheet metal straps 25 of a suitable metal, such as iron for instance, which extend along and are welded or otherwise suitably fastened to the respective lead-in conductors 18, 19 at either side of the coil-enclosed filament end f-1egs-213so as to overlie and clamp the said coil-enclosed filamentend' legs 23 to the lead-in wires at points opposite their welded connections thereto. v

' To rigidity the mount structure 17 and maintain the lead-in conductors 18, 19 and: 24) in fixed-relation to each other, suitable insulating hridges 2' 6; and flai -econnested: across-respective pairs of the lead in conductors to insulatively and rigidly tie them togethenas shown, The said bridges each comprise glass rod ZQhaying a flair f 1 9? r s embedded n am nd her f andwelde d to the adjacent lead inconductor,

' In accordance with the invention, a supplementany-or t x i beam ame fifla-o h h ame o as atins bu't o om w at, cwerwauaaerat s h n; e' ain fila e t 22 for. example around 400, watts, isprovided'on one side of and closely adjacent the.v main filament 22, Thesupplementaryfilament 30 i'sprefera-bly in thetform of alinear coil (i.e single coil) of tungsten wire extending transversely of the reflector axis and disposed approximately inthe focal plane. of the reflecting surface 6. Also asshown, the supplementary filament 30 is preferably disposed approximately symmetrical with respect to the vertical axial plane of the reflector section 2 and approximately parallel to the axial plane of thereflector section 2 which includes the two lead-in conductors 18, 19 for the main filament. In accordance with the invention, thesupplementary filament 30 is operated in parallel with, ancl positionedhorizontally and above the main filament 22, toprovide the landing beam. For this purpose the supplementary filament 30-is connected at one a ioh h rd nla d e ndv t r 10, n at the other end to .the inlead conductor 19'which therefore actsasacommon lead-in conductor for both themain and sup; n emant rrfi am nt As. o n the pp m n a y ameat. 3Q is prqvided with straight, i. e., uncoiled, end leg portions 31 Wl1ll'l extend in the directionof theaxis of the linear coil filament 39 and are suitably connected, as; by clampingfior instance, to the .inlead; conductors 19, 21);; 'Tothis end, theinleadmouductor ztllisofiset as indicated at 32 to provide an offset inner end; portion 33 which. extends,- closely alongside and approximately parallel to but spaced from the inner end-of the lead-in conductor 18, and is provided-with a hook 34 in which one end 31.0f the supplementaryfilament Sll'is clamped. Toprovide .the connection of the supplementary filament 30. to the lead-in conductor 19, the latter. is provided at its inner end with a short laterally or upwardlyextending leg portion 35whichis provided with a clamp-34in which .the othersend leg. 31 of thesupplementary filament is clamped. The laterally extending inner end or leg portion 35 of theinlead conductor 19 may be formed either by bending the inner end of the conductor 19'ortby forming the said leg portion 35 of the conductor 19 215 a sepa-. rate member and suitably securing it to the conductor 19, as by welding it thereto.

Because of the extended length of the supplementary filament 30, additional support means are provided-for supporting the said filament at one or more points in: termediate its ends, in order to maintain the linear coil filament 30in a more. or less horizontal positionwhen the lamp is'in operating position, and to prevent it from 4 l filament 22. The additional support means preferably comprises a support wire 36 embedded 'at one end in the glass rod 28 of the iusulative bridge 26 and provided at its other end with a loop 37 in which the supplementary filament 30 is caught and supported at the central region or mid-point thereof.

As a specific example of a lamp construction which has been found to 'be particularly suitable for the intended purpose, the major filament 22 is in the form of a coiled-coil of tungsten wire having a wire diameter of 17.9 mils and having primary or small coil turns of approximately 40 mils inside diameter and approximately 28 turns per inch and secondary or large coil' turns of approximately 6.9 millimeters outside diameter and approximately 7 turns per inch. The secondary or large diameter coil of the main filament 22 has a total length of approximately 9.2 millimeters. The supplementary filament 30 isin the form of a singlycoiled tungsten wire having a wire diameter of approximately 15.2 mils and the coils turns of which have an inside diameter of approximately 44.6 milsand a pitch of approximately 40 turns per inch; The coil length of the supplementary filament 30, i. e. the total length of the coiled portion of the filament, is approximately 29.6 millimeters. The major filament 22 is mounted symmetrically about the focus of the reflecting surface 6With the axis of its secondary or large coil turns coaxial with the axis of the reflecting surface 6. The supplementary filament 30 is disposed horizontally and approximately .250 inch above the major filament 22 (when the lamp'is in its operatingtively connect either the supplementary filament 30 alone,

or the two filaments ZZ-and 30 in parallel across an electric power supply having a voltage corresponding to the rated operating voltages of the two filaments, for example, 28 volts in the particular case set forth. When the line voltage is impressed across the horizontally disposed upper or supplemetnary filament 30 alone, a relatively wide flood or taxiing beam of the required lateral spread is producedhaving a maximum beam candlepower of the order of80,000 and 'a smoothly graded'i-ntensity distribution wherebyr the beam is entirely free ofdarkfareas or voids, ,When the line voltage is impressed across the main filament 22 and the supplementary filament 30 in parallel, alanding. beam is produced having a. generally circular-shaped centralhot spot portion, having a maxiheamcandlepower of the order. of 550,000 inthe oaseofa600 watt main filament 22 and a 400 watt supplementary filament 3.0. operated together in parallel at lOQflwatts, Withaslightly depressed widespread portion of lqwer. cand lepower to provide.foregroundillumination, ILwillJbeapparent-frorn the above description that I haye provided a-combinationairplane landing and taxiing lamp which not only will provide a concentrated high candlepower; (5003000 to 550,000 maximumlbeam; candlepower) beam suitable for airplane landing: purposes, .but which also will'provide, at "will, a widespread. appreciably lower: candlepower (i. e., approximately:80,000:maximum bearnxandlepower) beam 'admirably:suitable for-airplane taxiingtpurposesu The mount structure: 17'; is of simple construction and easy to manufacture; and-is sturdienand less subjectto vibrationrand' shock, and-resulting-damage, thaniprior multifilamentmount constructions which have beencproposecl for-this-service; Moreover, by arranging the filainents dor parallel operation to provide one of-the required beams, instead of for seriesopenation as in: the case of priorproposed lamp structures-thelilaments "are there'by--;rendererl less susceptible to variations --in -their operating life, as a 'result ofwhich-the-actual life 'ofthe woffilaimentswill conform more nearly totheirtheoretical sagging and contacting and shorting against the main design'lifez" I What I claim as new and desire to secure by Letters Patent of the United States is:

11. A light projection device comprising a concave reflector member having a reflector surface of approximately paraboloidal shape, a light source comprising a main filament in the form of a linear coiled coil disposed approximately coaxial with the axis of and approximately centered at the focus of said reflector surface, a supplementary filament in the form of a relatively long linear coil disposed horizontally and directly above and closely adjacent said main filament with its axis extending transversely to the reflector axis, said supplementary filament being arranged approximately symmetrically with respect to the vertical axial plane of said reflector, and current connection means connected to said filaments to selectively provide independent operation of said supplementary filament and parallel operation of both said filaments.

2. A light projection device as set forth in claim 1 wherein the said main filament has a wattage and voltage rating of the order of 600 watts and 28 volts and the said supplementary filament has a wattage and voltage rating of the order of 400 watts and 28 volts.

3. An electric incandescent lamp comprising a sealed envelope having an approximately paraboloidal reflector section and a light-transmitting window section, a light source mounted in said envelope and comprising a relatively high wattage main filament in the form of a linear coiled coil disposed approximately coaxial with the axis of and approximately centered at the focus of said re flector section and a supplementary linear coil filament disposed horizontally and directly above and closely adjacent said main filament with its axis approximately normal to the reflector axis, said supplementary filament being arranged approximately symmetrically with respect to the vertical axial plane of said reflector section, and current connection means including lead-in wires sealed into said envelope and connected to said filaments to selectively provide independent operation of said supplementary filament and parallel operation of both said filaments.

4. An electric incandescent lamp as set forth in claim 3 wherein the said main filament has a wattage rating of the order of 600 watts and a voltage rating of the order of 28 volts and the said supplementary filament has a wattage rating of the order of 400 watts and a voltage rating of the order of 28 volts.

5. An electric incandescent lamp comprising a sealed envelope having an approximately paraboloidal reflector section and a light-transmitting window section, and a mount sealed in said envelope and comprising a plurality of rigid lead-in conductors extending in spaced relation through and rigidly supported from the wall of said envelope, a pair of said lead-in conductors being disposed approximately in an axial plane of said reflector section and a third one of said lead-in conductors being disposed to one side of the plane of and between the said pair of leadin conductors, a relatively high wattage coiled-coil main filament disposed approximately coaxial with the axis of and approximately centered at the focus of said reflector section and connected at its ends across the said pair of lead-in conductors, and a supplementary linear coil filament disposed approximately parallel to the plane of said pair of lead-in conductors on the same side thereof as said third lead-in conductor and positioned closely adjacent said main filament at one side thereof with its coil axis approximately normal to the reflector axis, said supplementary filament being arranged approximately symmetrically with respect to the axial plane of said reflector section normal to said supplementary filament, one of said pair of lead-in conductors being provided at its inner end with a short laterally-extending portion connected to one end of said supplementary filament and the said third lead-in conductor being provided with an oifset inner end portion connected to the other end of said supplementary filament.

6. An electric incandescent lamp comprising a sealed envelope having an approximately paraboloidal reflector section and a light-transmitting window section, and a mount sealed in said envelope and comprising a plurality of rigid lead-in conductors extending in spaced relation through and rigidly supported from the wall of said envelope, a pair of said lead-in conductors being disposed approximately in an axial plane of said reflector section, an insulative bridge comprising an insulating member connected across said pair of lead-in conductors to rigidly tie them together, a relatively high wattage coiled-coil main filament disposed approximately coaxial with the axis of and approximately centered at the focus of said reflector section and connected at its ends across the said pair of lead-in conductors, a supplementary linear coil filament disposed approximately parallel to the plane of said pair of lead-in conductors and closely adjacent said main filament at one side thereof with its coil axis approximately normal to the reflector axis, said supplementary filament being arranged approximately symmetrically with respect to the axial plane of said reflector section normal to said supplementary filament and being connected at its ends to one of the said pair of lead-in conductors and to a third one of said lead-in conductors, and an auxiliary filament support member embedded in said insulating member and engaging said supplementary filament intermediate its ends to prevent sagging thereof into contact with said main filament.

References Cited in the file of this patent UNITED STATES PATENTS 2,142,384 Taylor Jan. 3, 1939 2,317,031 Cotman Apr. 20, 1943 2,441,824 Kurlander May 18, 1948 2,597,681 Smith May 20, 1952 

